During the last 20 years, linguistic data processing mainly has been seen as a tool to develop linguistic regularities (or detect irregularities) of a given natural language, especially to handle large textual databases ("Corpora"). A second motivation to use a computer was to test some theories or models of a language system (or a part of it) using a simulation program. As a result of both strategies, the "Saarbrücken Text Analysis System" has been implemented. At present, a very large lexical database is available to analyse written German texts morphologically and syntactically. The syntactic parser is able to handle every German sentence with more than 90% "correct" results. On the other hand, the development of large (textual) databases within different fields (e.g. law, patent specifications, medicine) is increasing rapidly. Therefore, a computer aided indexing system ("Computergestützte Texterschließung: CTX") has been developed at Regensburg and Saarbrücken University to improve the (even natural language oriented) access to textual data ("free text") applying linguistic strategies to information retrieval processes.\nMain results of feasibility studies, especially in the field of German Patent Documentation, are presented.